Sen. John McCain‘s absence from the Senate as he recovers from surgery for a blood clot has led the GOP leadership to postpone consideration of healthcare legislation that is already on the brink.

Senate Majority Leader Mitch McConnell said Saturday night that he was deferring action on the measure as McCain recovers at his home in Arizona. Surgeons in Phoenix removed a blood clot from above McCain’s left eye Friday. The 80-year-old Republican senator was advised by doctors to remain in Arizona next week, his office said.

“While John is recovering, the Senate will continue our work on legislative items and nominations, and will defer consideration of the Better Care Act,” McConnell said in a statement.

A close vote had already been predicted to pass the GOP healthcare bill, with all Democrats and independents coming out against it and some Republicans opposed or undecided. With the GOP holding a 52-48 majority, they can afford to lose only two Republicans. Vice President Mike Pence would break a tie for final passage.

A procedural vote expected in the coming days had been cast as a showdown over the measure designed to replace President Obama’s healthcare law, commonly called Obamacare.

McConnell and other GOP leaders have been urging senators to, at least, vote in favor of opening debate, which would allow senators to offer amendments. In recent days, GOP leaders have expressed optimism that they were getting closer to a version that could pass the Senate.

In Phoenix, Mayo Clinic Hospital doctors said McCain underwent a “minimally invasive” procedure to remove the nearly 2-inch clot and that the surgery went “very well,” according to a hospital statement. McCain was reported to be resting comfortably at his home in Arizona.

Pathology reports on the clot were expected in the next several days.

McCain is a three-time survivor of melanoma. Records of his medical exams released in 2008, when he was the GOP candidate for president, showed that he has had precancerous skin lesions removed. McCain also underwent a procedure to remove early-stage squamous cell carcinoma, an easily curable skin cancer, according to the records.